containerimageregistries

Container image registries are services that store and distribute container images. They host image manifests and the layered blob data that makes up a container image, and they implement the distribution interfaces defined by the Open Container Initiative (OCI). Registries can be public, such as those operated by major cloud vendors or community platforms, or private, hosted within an organization.

The core data model centers on images, identified by a repository name and a tag, with a content-addressable digest that uniquely identifies the image manifest. A manifest lists the image's layers and configuration, while each layer is a blob addressed by its cryptographic digest. Clients push and pull images through a registry API, typically over HTTPS, using authentication and authorization. Tags are mutable references; digests are immutable references that pin a specific image.

Architecturally, a registry service provides storage for blobs and manifests, a distribution API, and often ancillary services such as authentication, access control, and vulnerability scanning. Storage backends may be local disk, object storage, or distributed file systems. Many registries support features such as image signing, content trust, immutability policies, and geographic or policy-based replication.

Security and governance are central: image signing (for provenance), scan results, and role-based access control help prevent compromised images from entering pipelines. Automation tooling (CI/CD) interacts with registries to push built images, pull base images for builds, and pin versions by digest.

Common examples include public registries like Docker Hub, Google Container Registry, Amazon ECR, and Quay, as well as private registries such as Harbor or self-hosted OCI registries. Registries are a foundational component of modern container workflows, enabling scalable distribution, image versioning, and secure image provenance.